SURGICAL SITE INFECTIONS


the lower the skin bacterial count the better potential outcome, a study that looks only at bacterial skin counts has to give a good indication of a serious patient risk factor. Disinfectant products are often mixed with ethyl alcohol, which makes it difficult to form overall conclusions about another active ingredient during any time periods when it can be assumed the alcohol is still effective. More large, well-conducted RCTs with consistent protocols are still unlikely to provide the evidence we are searching for in respect to the effectiveness of one antiseptic preparation over another where patient outcome is ultimate measure. This is again due to the many other factors affecting outcome that cannot be controlled when undertaking such a trial.


Antiseptic surgical skin preparation There can be no doubt that antiseptic surgical skin preparation is important as a preventative step in preventing SSIs. The question that is unlikely to ever be answered is: “How much effect does it really have?”


It was this last question, and its inability to be answered, that caused the authors to undertake this study. As the study published in the New England journal which looked at the efficacy of CHG 2% versus PI (42), showed a significant reduction in SSI in the CHG group, the authors felt that this study would form the basis for our own study. In light of the recent revelations about the accuracy of some reporting on patient outcomes in studies on CHG49


, the authors feel that potential


Average CFU cm2 counts


2% Chlorhexidin Gluconate


70& Alcohol


5th generation Si Quat


2500 2250 2000 1750 1500 1250 1000 750 500 250 0


We should use patient outcome studies as a further validation of the results – and not the other way around.


inaccuracies did not affect the outcomes of this research. According to the New England


journal study, CHG 2% had a significantly positive effect on SSIs rates and therefore on patient outcome. The study reported that choice of antimicrobial agent and its concentration in solution are the two main factors affecting the number of bacteria on patient skin, and that this is linked to the patient outcome.40, 41, 43, 44, 45, 46, 47 Unfortunately, that study did not


compare CHG 2% with CHG 0.5% which is the concentration recommended by the CDC and others.39


of wound infection with the use of Ioban drapes compared with surgeries without drape use (12.1% without drapes vs 3.1% with drapes). With so much conflicting evidence


from patient outcome studies, for the moment at least we should consider the only practical method of determining the effectiveness of pre surgical preparations, is to measure and compare the skin bacterial counts prior to, during and for many hours after application.40, 41, 43, 44, 45, 46, 47


We should use


patient outcome studies as a further validation of the results - and not the other way around.


A factor not discussed in the


study is the potential that different areas of the body will have different pre-operative bacterial counts, which may also have been affected by pre-operative washing and/ or the type of surgical skin prep. When comparing the number of SSIs among patients prepared with DuraPrep to those prepared with PI solution in combination with iodophor-impregnated drapes, one study28


Similarly, one study23 Method


The authors chose the commonly used area of the longitudinal mid line incision of the abdomen as the area to sample. This area has also been used for many studies looking at levels of bacterial contamination.5,6,7,8,9,13,14


In addition,


reported no SSIs in either group. found no


statistically significant difference in the number of SSIs among patients prepared with a one-step iodophor- and-alcohol water-insoluble film with or without iodophor-impregnated drapes. In contrast, one study29


found statistically significant lower rates


and in light of the recent evidence that shows the adverse effect of alcohol with no other active agent skin flora over time,41 and as some clinicians still use 70% ethyl alcohol as a surgical skin preparation, this was included in the study.


2003 1772 1682 1684 1732


As the comparisons between CHG 2%, CHG 0.5% and PI have already been studied sufficiently to show that 2% Chlorhexidine is most effective and killing skin surface bacteria, in the short term, it was decided that the most relevant comparison would be to study the effect of CHG 2% versus 70% ethyl alcohol on its own and a newly released 5th generation SiQuat with a low ethyl alcohol content.


The authors considered the most 1179 863 621 171 48 Pre-treatment 5 min-post 154 15 1 hour post 148 13 2 hour post 11 4 hours post Each group had 100 test sites and an average CFU count was taken from each group. Comparison of 3 types of surgical skin prep solution. 32 l JULY 2018 l OPERATING THEATRE


relevant times for sampling of bacteria counts during a surgical procedure to be after five minutes, one hour post, two hours post and four hours post. The reason for these times is that aside from the emergency operating theatre, it is highly unlikely that if surgical skin prep is used correctly, “knife to skin” will take place within five minutes of the skin prep being applied. This means that the most relevant time to test initial effectiveness is as the blade


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